Melbourne's collective heart broke for the second time in 24 hours as word spread on Saturday that Sisto Malaspina, the co-owner of beloved Melbourne restaurant Pellegrini's Espresso Bar, had been killed in Friday's Bourke Street attack.

Mr Malaspina, who took over the Bourke Street institution with long-time friend Nino Pangrazio in 1974, died less than 400 metres from where Melburnians had been "warmed by his wide smile and his wonderful Italianness" for more than four decades.

Pellegrini’s was closed for business on Saturday, but that didn't stop thousands of customers from stopping by the restaurant which first opened its doors 60 years ago and is credited with kickstarting the city's cafe culture.

Chaplains were on hand to comfort mourners as they laid flowers and paid tribute to Mr Malaspina in a special book left outside by staff.

Mr Malaspina's business partner, Nino Pangrazio, broke down as he stood outside the restaurant and spoke of his long-time friend.

“I feel terrible,” Mr Pangrazio said. “We’ve been business partners since 1974 and we were friends for 10 years before that.

“He was just so happy-go-lucky and always with a smile. We hardly had a cross word in the whole time we worked together. Just devastated.”

Mr Pangrazio said he was informed of his business partner's death late on Friday night after receiving a call from a staff member.

Mr Pangrazio and Mr Malaspina, who had just become a new grandfather, had worked together at the restaurant just hours earlier.

Sisto Malaspina will be greatly missed behind the counter at Pellegrini's.Credit:James Boddington

"I left about 3 o'clock to go home for the week and then one of the staff rang me to ask had I seen Sisto. I thought he was there but obviously he wasn't and then I got a call around 10.30 to say the police had been in touch with the devastating news."

Mr Pangrazio said his friend's loss was already being felt by the wider Melbourne community.

"As you can see with all the people around here, there have been literally hundreds of people stopping by since about 7.30 this morning," he said. ''He was always a happy fellow and that's what people are remembering ... his happiness and his friendliness and his smile."

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Mr Pangrazio attributed his partner's "big personality" to much of the success of the business.

"His personality was right out in the forefront. People loved him and the business just seemed to grow every year. He will be missed by a lot of people."

Staff gathered in the laneway outside the restaurant throughout the day. Many broke down in tears while others offered comfort. Most were too upset to speak to the media.

However, a hand-written note in the window from staff paid tribute to "the best boss".

"Thank you for making us, your staff members, as part of your life. You always looked after us like family. You always said to have fun at work because we all worked so hard," the note said.

"Pellegrini's was your life. We will never forget all that you have done and given us all. We will love you forever and ever in our hearts."

Australian rock legend Jimmy Barnes, Victorian Premier Daniel Andrews and the Ambassador of Italy to Australia, Stefano Gatti, were among hundreds of high-profile customers who paid tribute to the "Melbourne icon."

“He was an amazing person and someone who’ll be missed,” Mr Andrews said. “He’ll be remembered for his life on Bourke Street not his death."

"We are devastated to hear this news. This was a beautiful man, generous and full of life. So undeserving of such a horrific ending," Barnes posted on Facebook.

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"We have taken our kids and grandkids to Pellegrini’s over the decades and our whole family sends our deepest condolences to Sisto's family and friends. What a shocking and sad week it has been. RIP my friend," he wrote.

Radio presenter Jo Stanley described Mr Malaspina as "a man who shaped Melbourne."

"Thank you for the memories Sisto — all of them connected to friendship and celebration. You are forever entwined with who I am. So much love to his family," Ms Stanley wrote on Twitter.

Members of Melbourne's close-knit restaurant community also expressed their shock at the loss of an "industry legend".

Denis Sabbadini, from another city dining institution, the Waiters Restaurant, said Melbourne had "lost someone special".

"You couldn't be in his presence without being warmed by his wide smile and wonderful Italianness," Mr Sabbadini said.

"He was the connsumate Italian restaurateur and a wonderful human being. I think the entire city is in shock.

"I fell on the bed and cried when I heard the news. He was the epitome of what a good cafe owner should be. And no one wore a scarf like he did," he added.

Former Hotel Sofitel and Hare & Grace chef Raymond Capaldi said it was "inconceivable" that someone who was the "embodiment of Melbourne" and had worked in Bourke Street for more than 40 years should die in such a way.

"Whenever you walked past Pellegrini's it gave you a little happiness in your heart," Mr Capaldi said.

"You would look inside and see Sisto in his cravat, making a coffee and you'd think 'You know what, this world is a good place'.

"You just imagined he would always be there and now he's not, and for it to end in such a tragedy makes it even more inconceivable."

"When my friend and I first visited Pellegrini's, Sisto not just invited us into his cafe, but into his heart as well. For such a big-hearted person to be killed in such a brutal fashion is painful. RIP Sisto."